Leykin 2008.

Methods	Randomized, double‐blind, active‐controlled study Medications administered 15 min before discontinuation of anesthesia
Participants	Type of surgery: functional endoscopic sinus Propacetamol group Entered/completing: 25/25 Age (mean, SD): 32 ± 10 Sex (male, %): 72 Parecoxib group Entered/completing: 25/25 Age (mean, SD): 34 ± 12 Sex (male, %): 76
Interventions	Intervention: 2 g propacetamol over 15 min Control: 40 mg IV parecoxib
Outcomes	Pain intensity (VAS) and derived SPID Opioid consumption (morphine) Patient satisfaction (categorical)
Source of funding	Not reported
Were treatment groups comparable at baseline?	Yes: demographics; type of procedure. Intraoperative and postoperative hemodynamic variables also reported to be similar, but no data shown.
Details of preoperative pain	Participants with chronic pain requiring major analgesics, sedatives, or corticosteroids were excluded
Notes	Participants had only mild pain at baseline
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomization
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding (performance bias and detection bias) All outcomes	Low risk	Study drugs mixed by physician not involved in study. Double‐dummy technique employed.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Analyses on ITT population, but no mention of imputation method
Selective reporting (reporting bias)	Low risk	All outcomes from Methods section reported in Results section
Size	High risk	Fewer than 50 participants per arm of the study (25 propacetamol, 25 parecoxib)